Industrial assays to evaluate the efficacy of vacuum pressure impregnation with commercial wood preservatives to eliminate the pinewood nematode, Bursaphelenchus xylophilus, and other nematodes from Pinus pinaster wood

Abstract

To demonstrate the efficacy of the vacuum pressure impregnation (VPI) with commercial wood preservative products to eliminate the quarantine organism, pinewood nematode (PWN), Bursaphelenchus xylophilus, and other nematodes from maritime pine (Pinus pinaster) wood, in vitro assays and industrial assays in horizontal industrial autoclave tanks were conducted. In vitro nematicidal activity assays through direct exposure of the PWN 3rd-stage dispersal juveniles, the resistance juvenile stage, extracted from naturally infected P. pinaster revealed 100% nematode mortality with three commercial wood preservatives. Nematode mortality was also assessed in VPI industrial assays with the three commercial wood preservatives using naturally PWN infected P. pinaster experimental units, with various diameters and sizes. After VPI treatment, the nematode mortality ranged from 99.9761 to 100%. After incubation, the mortality of the total number of nematodes increased and, in all sections, the nematode mortality was higher than 99.9981% and in some it was 100% indicating that wood impregnated with preservative products does not constitute an environment favorable to the reproduction and development of nematodes. Overall, our findings demonstrated that the efficiency of the VPI process results from the joint action of the physical effect of pressure and vacuum and of the nematicidal effect of the preservative product. VPI treatment can be considered a valuable approach to eliminate PWN and other nematodes from maritime pine wood avoiding the subsequent application of the heat treatment.